Organic light emitting diodes (OLED) are self-luminous devices with many advantages, such as very thin thickness, quick response, wide view angle, optimal resolution, high luminance, usable in flexible panel, and wide operating temperatures. OLED has been regarded as the new generation of the flat panel display technology after the thin film transistor liquid crystal display (TFT-LCD). The operating principle of the OLED is based on the light-emitting characteristics of the organic layer. As the electron and hole meet to form excitons through the organic layer, the energy promotes the light-emitting molecules to the excited state, and the light-emitting devices with different wavelengths are generated as the excited electrons fall into the ground state. The anode is made of ITO conductive films by sputtering or evaporating adheres to the glass or transparent plastic substrate, and the cathode is made of Mg, Al or Li, etc. The light-emitting region between two electrodes consists of many organic layers, including the hole injection layer (HIL), hole transport layer (HTL), emitting layer and electron transport layer (ETL). In actual production, other layers may be included to meet different requirements.
Although OLED has many advantages, the most commonly used fabrication technology for the OLED electrode insulator disclosed in the United State Patent Nos. U.S. Pat. No. 5,701,055, U.S. Pat. No. 5,962,970, U.S. Pat. No. 6,099,746, and U.S. Pat. No. 6,137,220 suggest that the insulator is produced by organic photoresists and two-mask processes. Further, the patents disclosed that positive photoresist is used to form an insulation photoresist on the substrate, and negative photoresist is used to form an inverse-triangular overhanging portion for sliver-like barrier rib. However, the insulator composed of organic photoresist is weak in mechanical strength and is easily damaged by external forces during fabrication. Besides, the insulator made of organic photoresist may precipitate organic materials that can affect the performance of other organic layers in the flat panel. Simultaneously, the insulator is not easily miniaturized for the physical limitations of the organic photoresist.